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最新推荐文章于 2022-02-25 19:38:17 发布

原创最新推荐文章于 2022-02-25 19:38:17 发布 · 350 阅读

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#c #string #include #null

#include <os.h>

#include <ctype.h>
#include <limits.h>

#define FL_UNSIGNED   1
#define FL_NEG        2
#define FL_OVERFLOW   4
#define FL_READDIGIT 8

static unsigned long strtoxl(const char *nptr, const char **endptr, int ibase, int flags)
{
const char *p;
char c;
unsigned long number;
unsigned digval;
unsigned long maxval;

p = nptr;
number = 0;

c = *p++;
while (isspace((int)(unsigned char) c)) c = *p++;

if (c == '-')
{
    flags |= FL_NEG;
    c = *p++;
}
else if (c == '+')
    c = *p++;

if (ibase < 0 || ibase == 1 || ibase > 36)
{
    if (endptr) *endptr = nptr;
    return 0L;
}
else if (ibase == 0)
{
    if (c != '0')
      ibase = 10;
    else if (*p == 'x' || *p == 'X')
      ibase = 16;
    else
      ibase = 8;
}

if (ibase == 16)
{
    if (c == '0' && (*p == 'x' || *p == 'X'))
    {
      ++p;
      c = *p++;
    }
}

maxval = ULONG_MAX / ibase;

for (;;)
{
    if (isdigit((int) (unsigned char) c))
      digval = c - '0';
    else if (isalpha((int) (unsigned char) c))
      digval = toupper(c) - 'A' + 10;
    else
      break;

if (digval >= (unsigned) ibase) break;

flags |= FL_READDIGIT;

    if (number < maxval || (number == maxval && (unsigned long) digval <= ULONG_MAX % ibase))
      number = number * ibase + digval;
    else
      flags |= FL_OVERFLOW;

c = *p++;
}

--p;

if (!(flags & FL_READDIGIT))
{
    if (endptr) p = nptr;
    number = 0L;
}
else if ((flags & FL_OVERFLOW) || (!(flags & FL_UNSIGNED) && (((flags & FL_NEG) && (number > -LONG_MIN)) || (!(flags & FL_NEG) && (number > LONG_MAX)))))
{
#ifndef KERNEL
    errno = ERANGE;
#endif

    if (flags & FL_UNSIGNED)
      number = ULONG_MAX;
    else if (flags & FL_NEG)
      number = (unsigned long) (-LONG_MIN);
    else
      number = LONG_MAX;
}

if (endptr != NULL) *endptr = p;

if (flags & FL_NEG) number = (unsigned long) (-(long) number);

return number;
}

long strtol(const char *nptr, char **endptr, int ibase)
{
return (long) strtoxl(nptr, endptr, ibase, 0);
}

unsigned long strtoul(const char *nptr, char **endptr, int ibase)
{
return strtoxl(nptr, endptr, ibase, FL_UNSIGNED);
}

long atol(const char *nptr)
{
int c;
long total;
int sign;

while (isspace((int)(unsigned char) *nptr)) ++nptr;

c = (int)(unsigned char) *nptr++;
sign = c;
if (c == '-' || c == '+') c = (int)(unsigned char) *nptr++;

total = 0;
while (isdigit(c))
{
total = 10 * total + (c - '0');
c = (int)(unsigned char) *nptr++;
}

if (sign == '-')
return -total;
else
return total;
}

int atoi(const char *nptr)
{
return (int) atol(nptr);
}

int atoi(const char * string)